Persulfate/metal mixtures for repulping and/or decolorizing paper

ABSTRACT

Repulping and/or decolorizing formulations and mixtures which include a catalytic amount of a salt of a metal such as copper, iron, silver, or nickel; a persulfate; and from 0-10% saccharide. Formulations containing a carbonate, sesquicarbonate or bicarbonate for adjusting pH are preferred. A method of repulping and/or decolorizing broke, whether containing wet strength resin or not, using the formulations or mixtures of the ingredients in the formulations.

This application is a divisional of application Ser. No. 08/108,202,filed 17 Aug. 1993 now abandoned.

FIELD OF THE INVENTION

The invention relates to paper reprocessing, and more particularly tothe repulping and/or decolorizing of wet strength broke.

BACKGROUND OF THE INVENTION

Broke is waste or off-specification paper which is to be recycled. It isgenerally more desirable to recycle the broke by a process calledrepulping than it is to merely dispose of the broke as waste paper.

In the repulping process, the cellulose fibers which make up the brokeare separated from the broke to make them usable for manufacturingpaper. In the process, wet strength resin (such as apolyamide-epichlorhydrin resin) used to enhance the strength of thepaper must be broken down since it binds the cellulose fibers together,forming a water impervious coating which impedes the repulping processgoal of separating the cellulose fibers. Representative paper productscontaining wet strength resins are paper towels, tissues, and foodwrappings. Typically, paper having wet strength resins will retain atleast 15% of the paper's dry strength when wet. Paper without wetstrength resin generally retains only 2-7% of its dry strength when wet.

Oxidation facilitates the break down of the wet strength resin to permitseparation of the cellulose fibers. Traditionally, hypochlorite,particularly sodium hypochlorite, has been used by paper mills as theoxidizing agent, and has generally been used within a narrow, carefullymaintained pH range and within a temperature range of from about 122° F.(50° C.) to 151° F. (66° C.). After broke has been successfullyrepulped, an agent is added to neutralize the remaining chlorine.

Environmental issues have been raised concerning the use of hypochloritefor repulping. These concerns range from the formation of suspectedcarcinogenic organic halides which are adsorbed by the pulp, to theproblem of chloroform emission, and to the problem of adding toxicchlorinated hydrocarbons to the effluent stream. For these reasons,non-halogen containing compounds such as persulfates have been used tooxidize wet strength resin during the repulping process.

When recycling broke, sometimes the broke must be decolorized. This isachieved by decomposing the colorants used to color the broke. Colorantsare chemicals that interact with light, causing the absorption ofselective wavelengths in the visible spectrum (400 to 700 nm).Wavelengths that are reflected (not absorbed) yield colors that areperceptible to the human eye. Colorants include both pigments and dyesand can be added during the paper making process to produce coloredpaper. Pigments are water insoluble compounds that are generallyunbleachable. Dyes are water soluble, and are more commonly used thanpigments to produce colored papers.

Dye molecules have two functional parts: the chromophore and theauxochrome. The chromophore is the portion that lends color to the dye.The auxochrome is the portion that anchors the dye to the cellulosefiber.

Chromophores are conjugated, that is, they contain a network ofalternating single and double bonds. Light interacts with the conjugatednetwork and is absorbed by electrons within the network. Wavelengthsthat are not absorbed by the network are reflected to produce the colorin the fiber.

Conjugated networks vary in length, the length generally correspondingto a dye color. As the number of conjugated bonds in the networkincreases the colors change from yellow to orange to red to violet toblue to brown to black and the networks become more susceptible tooxidation or free radical attack. Correspondingly, it can be difficultto decolorize yellow, orange, and red dyes due to their low degree ofconjugation.

There are many different dye structures, but there are two main dyeclasses used by the paper industry: azo dyes and stilbene dyes. Stilbenedyes are less popular than azo dyes but are more stable to manyoxidants, including chlorine.

An azo dye is a chemical compound containing at least onenitrogen-nitrogen double bond (azo functional group), which is subjectto oxidative attack. A stilbene dye is an aromatic system containing aseries of carbon-carbon double bonds which are more resistant tooxidative attack than are the nitrogen to nitrogen double bonds found inazo dyes.

To repulp and/or decolorize and effectively meet environmentalrequirements, it would be a breakthrough to find a suitable compositionwhich would permit separation of the fiber without destruction of thecellulose, yet permit altering the chromphore to decolorize. Chlorinecan repulp and/or decolorize but presents undesirable environmentalproblems. Persulfates can be used for repulping but are generallyineffective as decolorizing agents.

SUMMARY OF THE INVENTION

We have discovered that a soluble salt of copper, iron, silver, ornickel used in conjunction with a persulfate salt provides thebreakthrough by enhancing the decolorizing and/or repulping of brokeover a wide pH range whether or not used as a formulated product. Such acombination is especially useful in treating wet strength broke.

We have also discovered that a saccharide, such as a monosaccharide,polysaccharide, or cis-alpha-hydroxy saccharide used in conjunction witha soluble copper, iron, silver, or nickel salt, and with a persulfatesalt further enhances the decolorizing and/or repulping of the brokeover a wide pH range.

These ingredients whether added separately to form a mixture in situ, oradded as a formulation can be used in a method for repulping and/ordecolorizing broke, particularly wet strength broke.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Soluble copper, iron, silver or nickel salt activates persulfate to makeit more reactive towards colorants, or wet strength resins, such asthose used in paper manufacture, than persulfate alone. The use of a pHadjuster, such as an acid or a base with the metal salt and persulfatecan further enhance the repulping and/or decolorizing efficacy of thepersulfate by providing a pH within the range of from 2 to 11. Additionof a saccharide to the above mixture can sometimes further enhancedecolorizing and/or repulping efficacy of the persulfate.

Persulfate can repulp broke, particularly in the presence of base, evenin the absence of the metal salt. However, the above described saltsenhance repulping and make decolorization possible. These salts are usedat such low concentrations that their effect appears catalytic. Althoughit is not known whether or not true catalysis is occurring, for purposesof this description, the terms "catalyst" or "catalytic amount" will beused when referring to the salt concentration, since the amount of metalsalt required for repulping and/or decolorization is extremely low.

The effect of these metal salts on repulping can be further enhanced bythe presence of a saccharide, such as a polysaccharide or amonosaccharide. The most preferred saccharides for either repulping ordecolorizing are the cis-alpha-hydroxy saccharides such as ascorbicacid, D-mannitol, and D-sorbitol.

Preferred pH adjusters for repulping and/or decolorizing, include aloneor in combination one or more of the following: sodium carbonate, sodiumbicarbonate, and sodium sesquicarbonate.

In this specification and in these claims:

a) The term "about" herein shall be inferred when ranges, dosages,weight percent or other numerical designations are described, unlessotherwise specified.

b) The term "persulfate" includes any persulfate salt including sodiumpersulfate, potassium persulfate, and ammonium persulfate, unlessotherwise specified.

c) The terms "carbonate", "sesquicarbonate" and "bicarbonate" includealkali metal, alkaline earth metal and ammonium salts of carbonate,sesquicarbonate or bicarbonate.

d) The term "dry" indicates a composition or substance which does notfeel moist to the touch. A dry composition can have water of hydration.

e) The term "owf" is a dosage term which means based on the dry weightof fiber.

f) The term "consistency" is the broke weight percent based on theweight of the water used for repulping.

g) The term "percent" is a weight percent, unless otherwise expresslyspecified.

h) The term "soluble" when used in reference to a salt, indicates a saltthat based on its solubility product constant can provide 0.5 ppm ormore of solubilizable metal ion in an aqueous medium.

i) The term "BT-100" signifies a formulation containing 75% sodiumpersulfate and 25% sodium carbonate.

j) The term "% owf" means the percent of decolorization and/or repulpingtreatment used based on the weight of broke fiber being treated. Thisterm is equivalent to the term "percent furnish."

k) The term "pHi" means initial pH.

l) The term "pHf" means final pH.

The compositions of this invention enhance the repulping of wet strengthbroke and are particularly effective in decolorizing the dyes in suchbroke. In one aspect of this invention a persulfate, and one or more ofa metal salt of copper, iron, silver or nickel can be used forrepulping, for decolorizing, or for both. These components can be addedseparately to the broke or in combination as a formulation, with orwithout a pH adjuster.

Generally, the formulations of this invention contain from 51 to 94%persulfate; from 4 to 43% pH adjuster; from 0 to 10% cis-alpha-hydroxysaccharide; and a catalytic amount of the metal salt. More preferably,the formulation contains from 61 to 85% persulfate; from 14 to 39% baseselected from the group consisting of carbonate, bicarbonate andsesquicarbonate and from 0.05 to 3% metal salt. More preferably, theformulation contains from 70 to 80% persulfate; from 20 to 29%carbonate; and from 0.1 to 2% copper salt. More preferably, theformulation contains 1 to 6% cis-alpha-hydroxy saccharide, mostpreferably from 1 to 3% cis-alpha-hydroxy saccharide.

The precise amount of persulfate, saccharide, pH adjuster and metal saltrequired for an effective composition for repulping or decolorizationwill depend on use conditions such as pH, the type or quantity ofoxidizable material, and temperature, and depending on those conditionscan vary from the values given above.

Exemplary pH adjusters include bases and acids. Exemplary bases includeone or more of the following: sodium carbonate, sodium bicarbonate,potassium carbonate, potassium bicarbonate, calcium carbonate, sodiumsesquicarbonate, potassium sesquicarbonate, and the like; these areparticularly useful in dry formulations, but may be added separately.Other bases such as sodium hydroxide can also be used, particularlywhere separate addition of the components of this invention ispracticed.

Acids which may be used as pH adjusters include the mineral acids suchas hydrochloric acid and sulfuric acid, organic acids such as acetic, orany of the other acids known to those of ordinary skill in the art.

The preferred saccharides include ascorbic acid, D-sorbitol, andD-mannitol. Other saccharides can be used as long as they have nogreater tendency to reduce the catalyst than D-mannitol, preferably,D-sorbitol, more preferably, or ascorbic acid, most preferably.

The catalytic metal salts include those salts which are sufficientlysoluble in water to provide 1 ppm of solubilized metal ion. Suitablemetals include copper, iron, silver, and nickel. Representativecounterions include sulfate, chloride, nitrate, and other counterionswhich permit a reasonable degree of water solubility. These metal saltscan include ligands.

The compositions of this invention are used to repulp and/or decolorizebroke. In the repulping process, water and broke are placed in a vessel,and agitated. Agitation consists in using a mixer/shearer such as iscommonly used in the industry to mix the broke, water, and chemicals inthe repulping operation, as well as to comminute the broke. The use of amixer/shearer is equivalent to using a separate mixing and shearingdevice. The chemicals of this invention can be added prior to or duringagitation.

Different types of site addition can be used. The components can bemixed on site in dry form and fed as a dry mixture. The components canbe added simultaneously to the repulping mixture as a dry powder, aslurry, a solution, or in any other suitable manner. Generally, thecomponents can be added in any order.

Moreover, the repulped broke may be introduced directly into the papermaking process as a slurry without further modification. Paper can bemade from the repulped broke by separating the cellulose fibers from theslurry and introducing the fibers to a fourdrinier upon which paper ismade.

The embodiments of this invention work best if the temperature of thesystem is greater than 50° C. A temperature within the range of 40° C.to 75° C. is generally sufficient to activate the persulfate and/orcopper ion to support the oxidation of colorant or wet strength resinduring repulping. Higher temperatures can be used, but generally are notrequired.

In the process, the resulting mixture is agitated for sufficient time todefiber the broke to produce a satisfactory pulp. The time can varydepending on factors such as concentration of the persulfate, base oracid, activator, consistency, amount of oxidizable material, pH, andtemperature. The use of the persulfate/pH adjuster/metal salt with orwithout saccharide, whether or not formulated as a dry blend provides asignificant time advantage over the use of persulfate alone or basealone.

Repulping time is dependent on the nature of the broke. Broke whichcontains a high percentage of wet strength resin requires a longertreatment time than broke which contains less wet strength resin.

The requirements for decolorization and for repulping need not be thesame. However, repulping is generally completed before decolorization iscompleted.

Although a wide pH range is generally usable in the instant process, therepulp or decolorization time can be affected by the final system pH.Generally, a pH range of from 2 to 11 can be used for either repulpingor for decolorization. However, a pH range of from 7 to 10 is preferredfor repulping and/or for decolorizing. Most preferred is a pH thatvaries during the process, since different chromophores appear to bebest oxidized at different pH.

In a preferred aspect of this invention a variable pH in the 7 to 8.5range is achieved by employing a base such as an alkali metal, alkalineearth metal or ammonium salt of carbonate, sesquicarbonate, orbicarbonate as part of the decolorizing mixture or formulation to permitthe pH to decrease as oxidation occurs. Addition of one of these basesseparately or as part of the decolorizing formulation can provide aninitial pH of 8.5 or higher. As decolorization progresses, acid productsare formed which gradually lower the pH.

Other pH adjusters can be used. These include sodium hydroxide, sulfuricacid and other acids or bases known to those skilled in the art.

Final and initial pH compatible with process plant systems arepreferred. It is desirable to select a pH range which optimizes therepulping process, the decolorization process or both. However, manytimes pH control is based on the desirability of obtaining a final pHfor the system which is compatible with other stages of paperproduction. For example, when a satisfactory pulp is produced, theprocess water is typically mixed with processed pulp from other sources,which may be acid, neutral, or basic. Or water from other processes maybe used as the makeup water for the broke repulping process.

Additional pH adjustment to accommodate these other stages is avoided byusing the compositions of this invention as follows:

The ratio of persulfate to base can be selected to provide a neutral pHeffect. That is, as the persulfate is consumed during the oxidationprocess, bisulfate is produced. A neutral pH effect is achieved byadjusting the amount of base used to offset the reduction in pHattendant acid production during repulping. Normally, the bisulfateproduced from the persulfate is the only acid which need be considered.However, if large amounts of other acids are produced from decompositionof the fiber or the resin, those acids may have to be considered.

Alternatively, if the pH of one process, for example, the paper makingprocess, differs from the pH of the repulping and/or decolorizingprocess, adjustments in pH can be made for the repulping and/ordecolorizing process by varying the persulfate:(acid or base) ratio toavoid any need for subsequent pH adjustment. Thus, acid, neutral oralkaline paper making processes can be accommodated without requiring anadditional pH adjustment step. It will be evident that such adjustmentscan be routinely achieved in light of the guidelines set forth herein.Consideration would be given to the actual pH and alkalinity of thesystem, to the acid expected to be generated and to the additionalalkalinity provided by the addition of a formulated persulfate product,in view of standard chemical equations and calculations for the system.

In addition to pH, an effective dosage of the composition is desired.Dosages of 0.5% owf or greater are generally effective. The effectivedosage is dependent upon system conditions, and can be determined usingthe information disclosed herein. A preferred dosage is 1% to 15% owf. Amore preferred dosage is 2% to 12% owf. Higher or lower dosages than theones specified herein can be effective depending on the change in systemparameters.

The parameters indicated above are useful in repulping wet strengthbroke.

The following examples further illustrate the invention without limitingthe scope thereof.

EXAMPLES Determination of the Degree of Decolorization

In all of the decolorization examples herein, which provided thebrightness, lightness, red/green(alpha), or yellow/blue(beta) readingsfor the paper being treated, an Elrepho Datacolor 2000 Reflectance meterat setting R-457 was used. All readings were taken from handsheetsavailable before treatment or prepared from the treated broke. Thereported results were an average of three readings.

Red/green and yellow/blue readings quantified the decolorizationcapability of each treatment with red and yellow having positive valuesand green and blue having negative values. For example, in the tablesprovided herein, a zero value in either column signifies completedecolorization. Thus, positive numbers signify predominance of red oryellow, while negative numbers signify the predominance of green orblue. Absolute values of 3 or less for either red/green or yellow/bluesignify an acceptable degree of decolorization for most paper makingoperations, as paper having these color values are perceived to be whitewhen viewed by an unaided human eye. Higher absolute color values can beacceptable depending on the requirements of the end user.

Procedure for Repulping and/or for Decolorizing Wet Strength Broke

In the standardized process for repulping and or decolorization of wetstrength and non-wet strength broke described below, unless otherwiseindicated, oxidation of chromophores, or of the resin used in wetstrength broke, or of other components of the broke was accomplished andmeasured by TAPPI (also known as The Technical Association of the Pulpand Paper Industry) method T-205-om81 for repulping wet strength broke,including any variances.

1500 mL of 70° C. (158° F.) water was poured into a 2 liter Pyrex®beaker. The pH was adjusted and the desired repulping composition added.The resulting slurry was then poured into a preheated disintegratorvessel which was adjusted to a maintenance temperature of 70° C. (158°F.). 20 grams of pre-cut 1 inch broke squares were then added, and thedisintegrator was started with continuous sample mixing at 2800 rpm.Temperature readings and 10 mL aliquots were taken every 5 minutes.These 10 mL aliquots were diluted to 200 mL with tap water, and thencompared with standard samples for stages 1 through 6 (described below).Sampling continued until a stage 6 sample was obtained; however, if astage 6 sample was not obtained for repulping or if an absolute colorvalue of 3 or less was not obtained for decolorization or if therequired degree of decolorization was not obtained, then the, samplingceased at the end of 60 minutes. The pH, temperature, and residualoxidizer and/or color measurements of the final sample were thenrecorded.

Generally, as paper was being repulped, if it was colored, it was alsobeing decolorized. Similarly, if the paper was being decolorized it wasalso being repulped. The standards used for determining the efficacy ofrepulping were different from the standards used for determining theefficacy of decolorization. These are described herein.

Standard Samples for Repulp Stages 1-6

During the above described TAPPI repulping method the pulpcharacteristics changed from clumps of cut up resin coated paper inwater to a relatively uniform mixture of free cellulose fiber and water(stage 6).

Repulp stages were determined by direct comparison to pre-made standardsmade according to the above TAPPI repulping method. These standards werecharacterized and designated as "stages", starting with stage 1 andending with stage 6, as follows:

Stage 1 was characterized primarily as a broke having numerous largefiber flakes.

Stage 2 was characterized as a broke having large flakes, and smallflakes.

Stage 3 was characterized as a broke having primarily numerous smallfiber flakes.

Stage 4 was characterized as a broke having primarily few small flakes,and numerous bonded fibers.

Stage 5 was characterized as a broke which primarily has finelyseparated fibers and a few bonded fibers.

Stage 6 was characterized as a broke which has been repulped to finelyseparated fibers.

A fuller understanding of the above described repulping stages isprovided by the following review of the process.

The initial broke could be cut up paper composed of 1 inch squares, or,it could be a roll of waste paper, which is comminuted by a blade, suchas a high shear impeller, to a paper composed primarily of numerouslarge flakes. As the broke is repulped, it typically becomesincreasingly smaller. Ideally, repulping produces a Stage 6 pulpcomposed of completely separated fiber. In practice, however, a Stage 5product consisting primarily of separated fibers and a few bonded fibersis generally acceptable.

The paper produced from repulped broke is finer, the more complete thefiber separation in the pulp. Generally, the less completely separatedthe fiber, the greater degree of dumpiness and surface irregularity inthe finished paper good.

Example 1 pH of 1% Solutions of Formulated Broke Treatment

The pH of a 1% solution of a formulated product containing 75% sodiumpersulfate and 25% sodium carbonate was determined as described in Table1 below.

In the test procedure, one gram samples of formulated product were addedto 99 grams of the water being evaluated. After 5 minutes mixing, the pHof the system was measured. The results are provided below andsummarized in Table 1.

                  TABLE 1                                                         ______________________________________                                        pH of 1% Aqueous Solutions                                                    EX      (1)pH.sub.i                                                                           (2)pH.sub.f  (3)pH.sub.i                                                                         (4)pH.sub.f                                ______________________________________                                        75% Sodium Persulfate/25% Sodium Sesquicarbonate                              1       5.07    10.22        7.49  10.03                                      2       4.50    10.26        7.23  10.02                                      75% Sodium Persulfate/25% Sodium Carbonate                                    1       5.27    11.46        6.99  11.08                                      2       4.50    10.26        7.01  11.10                                      ______________________________________                                         (1)pH of deionized water prior to addition of persulfate formulations. Th     subscript "i" signifies an initial pH.                                        (2)pH of deionized water five minutes after addition of formulations. The     subscript "f" signifies a final pH                                            (3)pH of tap water prior to addition of persulfate formulations.              Alkalinity of tap water = 80 ppm; total hardness = 110 ppm. The subscript     "i" signifies an initial pH.                                                  (4)pH of tap water five minutes after addition of formulations. The           subscript "f" signifies a final pH.                                      

Table 1 above demonstrates that pH increases rapidly when persulfateformulated at 75% persulfate and 25% base is added to an aqueoussolution. In Table 1, the pH increase occurred in less than 5 minutes.

Example 2 Effect of Formulated Sodium Persulfate on pH Before and AfterRepulping Wet Strength Broke

Repulping experiments were conducted in tap water. In these experimentsthe repulping formulation was added to a repulping mixture preparedaccording to the TAPPI method described above. The repulpingformulations were dry blends of 75% sodium persulfate ("SP") and 25% ofeither sodium sesquicarbonate or sodium carbonate as indicated in Table2 below.

                  TABLE 2                                                         ______________________________________                                        Formulation                                                                            SP/Sodium Sesquicarbonate                                                                     SP/Sodium Carbonate                                  (% OWF)(1)                                                                             (2)pH.sub.i                                                                           (3)pH.sub.a                                                                           (4)pH.sub.f                                                                         (2)pH.sub.i                                                                         (3)pH.sub.a                                                                         (4)pH.sub.f                        ______________________________________                                        0.50     7.4     7.9     7.7   7.4   8.5   8.0                                1.00     7.5     8.4     7.2   7.4   8.8   7.4                                1.50     7.6     8.5     7.3   7.4   9.1   7.5                                2.00     7.8     8.6     7.3   7.6   9.2   7.4                                2.50     7.6     8.9     7.4   7.4   9.3   7.7                                ______________________________________                                         (1)% OWF = Addition of the formulated material based on the weight of the     broke fiber.                                                                  (2)pH.sub.i = initial pH of tap water                                         (3)pH.sub.a = pH of the tap water after addition of treatment.                (4)pH.sub.f = Final pH of the wet strength broke solution after repulping     was completed.                                                           

The experiments depicted in Table 2 show that a 75% persulfate, 25% baserepulping formulation was self neutralizing for the tap water used. Inthe absence of sodium carbonate, sodium sesquicarbonate, sodiumbicarbonate, or other base the acid bisulfate produced when thepersulfate oxidizes the wet strength resin would be expected to decreasethe pH to less than 7.

Example 3 Decolorization with Various Copper Salts

In this example, the efficacy of several sources of copper whichincluded cuprous as well as cupric salts were examined. A rose-coloredtissue paper containing wet strength resin was used. Formulations wereprepared and mixed on a rollermill for one hour (hereinafter termed the"rollermill procedure") and then used in the standard repulpingprocedure described herein. The formulations were applied at 5% owf. Theresults are reported in Table 3.

                  TABLE 3                                                         ______________________________________                                        Decolorization with Various Copper Salts                                                                  (+ / -) (+ / -)                                   Treatment                                                                              Brightness                                                                             Lightness Red/Green                                                                             Yellow/Blue                               ______________________________________                                        5% BT-100                                                                              51.68    78.08     13.3    2.0                                       CuO.sup.1                                                                     5% BT-100                                                                              51.60    78.12     13.1    2.2                                       Cu.sub.2 O.sup.2                                                              5% BT-100                                                                              53.73    79.87     9.9     3.2                                       CuCl.sup.3                                                                    5% BT-100                                                                              52.08    78.82     10.7    2.9                                       CuSO.sub.4.sup.4                                                              5% BT-100                                                                              57.05    81.90     7.1     3.4                                       CuCl.sup.5                                                                    5% BT-100                                                                              59.47    83.71     5.3     4.3                                       CuSO.sub.4.sup.6                                                              ______________________________________                                         .sup.1 Cu added at 0.5 ppm from cupric oxide.                                 .sup.2 Cu added at 0.5 ppm from cuprous oxide.                                .sup.3 Cu added at 0.5 ppm from cuprous chloride.                             .sup.4 Cu added at 0.5 ppm from cupric sulfate pentahydrate                   .sup.5 Cu added at 1.0 ppm from cuprous chloride.                             .sup.6 Cu added at 1.0 ppm from cupric sulfate pentahydrate              

Table 3 illustrates the effectiveness of various copper compounds underalkaline conditions at decolorizing a rose-colored tissue paper. Becausethe paper was rose-colored, the reduction in red color was the mostsignificant. The insoluble copper oxides were not very effective asdecolorizers. The more soluble copper chloride and copper sulfate weremore effective than the less soluble copper salts, even at less than 1ppm. Copper sulfate at 1 ppm was the most effective copper salt testedin this example, producing the lowest red value.

Example 4 Experimental Decolorization Formulations I

The eight formulations described in Table 4 were prepared and evaluatedfor their ability to decolorize rose-colored, wet strength paper.Ascorbic acid (AscOH)/iron salt, or AscOH/copper salt were added toalkaline or neutral sodium persulfate mixtures using the followingprocedure: To a 250 mL Erlenmeyer flask 200 mL tap water was added andheated to 70° C. in a microwave oven. Then a 2. g sample of therose-colored tissue paper was added to each flask. A one gram portion ofeach formulation was then added to each of eight flasks. A 1.0 g of aformulation containing only 75% persulfate and 25% carbonate was addedto a ninth flask. Observations were recorded over a two hour time span.

The formulations used are described in Table 4 below.

                  TABLE 4                                                         ______________________________________                                        Experimental Decolorization Formulations I                                    Formulation                                                                            Chemical Addition      % w/w                                         ______________________________________                                        1        75% persulfate/25% carbonate.sup.1                                                                   97.44                                                  Ascorbic acid          2.42                                                   (NH.sub.4).sub.2 Fe(SO.sub.4).sub.2.6H.sub.2 O                                                       0.14                                          2        75% persulfate/25% carbonate.sup.1                                                                   97.44                                                  Ascorbic Acid          2.42                                                   CuSO.sub.4 .5H.sub.2 O 0.14                                          3        75% persulfate/25% carbonate                                                                         95.44                                                  Ascorbic Acid          4.28                                                   (NH.sub.4).sub.2 Fe(SO.sub.4).sub.2.6H.sub.2 O                                                       0.28                                          4        75% persulfate/25% carbonate.sup.1                                                                   95.44                                                  Ascorbic Acid          4.28                                                   CuSO.sub.4.5H.sub.2 O  0.28                                          5        75% persulfate/25% carbonate.sup.1                                                                   97.44                                                  Ascorbic Acid          2.42                                                   (NH.sub.4).sub.2 Fe(SO.sub.4).sub.2.6H.sub.2 O                                                       0.14                                          6        75% persulfate/25% carbonate.sup.1                                                                   97.44                                                  Ascorbic Acid          2.42                                                   CuSO.sub.4.5H.sub.2 O  0.14                                          7        75% persulfate/25% sulfate.sup.2                                                                     95.58                                                  Ascorbic Acid          4.28                                                   (NH.sub.4).sub.2 Fe(SO.sub.4).sub.2.6H.sub.2 O                                                       0.14                                          8        75% persulfate/25% sulfate.sup.2                                                                     95.44                                                  Ascorbic Acid          4.28                                                   CuSO.sub.4.5H.sub.2 O  0.28                                          9        75% persulfate/25% sodium carbonate                                                                  100                                           ______________________________________                                         .sup.1 = 75% sodium persulfate/25% sodium carbonate.                          .sup.2 = 75% sodium persulfate/25% sodium sulfate.                       

In Table 4 above, Formulations 1 and 2, containing 75% persulfate/25%carbonate/Ascorbic acid/metal salt worked best causing rapiddecolorization. Formulation 4 containing an increased level of coppersalt was next best. Formulations 3 and 5-8 exhibiting 40-70% colorreduction was next best. Formulation 9 containing just 75%persulfate/25% carbonate was least effective.

The 75% persulfate/25% carbonate formulations were better than theformulations containing 75% persulfate/25% sulfate. It is believed thatthe improvement was primarily due to the higher pH (9-10) afforded bythe carbonate as compared to the lower pH afforded by the sulfate.

For the 75% persulfate/25% carbonate formulations small amounts ofcopper worked well, and generally the smaller amount of copper saltprovided better results. Copper salts were superior to the iron saltsbecause residual iron imparted a slight yellow-brown color to the pulp,but both salts enhanced the decolorization of the paper.

Example 5 Experimental Decolorization Formulations II

In this example, 75% persulfate/25% carbonate with and without copperwas evaluated for decolorizing six paper samples (Grey, Chartreuse,Cherry, Green, Ivory, and Blue) which did not contain wet strength resinusing the following procedure:

Samples were cut into 1 inch squares. For each of the six sample,colors, a 3.0 g sample paper was added to each of three separateerlenmeyer flasks which were placed in a row to provide six columns offlasks with a separate row for each of the six different colors.Chemicals were not added to the first flask in the row of broke samples.Each flask in the second row was treated with 0.50 g of a 75%persulfate/25% carbonate formulation. Row three samples were treatedwith a 0.50 g 75% persulfate/25% carbonate/0.01 g ascorbic acid (AscOH),and 0.001 g CuSO₄ formulation.

Each flask then received 100 mL of tap water preheated to 70° C. Allflasks were gently swirled to mix chemicals. Observations were recorded16 hours after treatment. The experimental results obtained arepresented in Table 5below.

                  TABLE 5                                                         ______________________________________                                        Experimental Decolorization Formulations II                                   Observations After 16 Hours                                                   Green       Ivory   Blue   Chtrs  Cherry                                                                              Grey                                  ______________________________________                                        Row 1   NR.sup.1                                                                              NR      NR   NR     NR    NR                                  (Untrt)                                                                       Row 2   yellow.sup.2                                                                          lighter white                                                                              yellow.sup.2                                                                         cherry.sup.3                                                                        orange.sup.4                        (BT-100)                                                                      Row 3   yellow.sup.5                                                                          lighter white                                                                              yellow.sup.6                                                                         cherry.sup.7                                                                        brown.sup.8                         (BT-1 100/                                                                    AA/Cu)                                                                        ______________________________________                                         .sup.1 No reaction.                                                           .sup.2 Formulation appeared to react with the blue dye component only.        .sup.3 Residual cherry color, approximately 30% reduced.                      .sup.4 Paper turned orange.                                                   .sup.5 Same as 2 but lighter yellow shade.                                    .sup.6 Lighter yellow than chartreuse in row 2.                               .sup.7 Color approximately 50% reduced.                                       .sup.8 Paper turned brown.                                               

In Table 5 above the untreated, colored paper in the first row did notundergo a color change. The second row paper treated only withpersulfate/carbonates showed some decolorization: the blue dyes werecompletely eliminated, the green paper turned to yellow, and othercolors were slightly faded. The third row formulation,persulfate/ascorbic acid/copper, exhibited improved decolorization: bluedyes were eliminated, green paper turned yellow, and other colors weremarkedly reduced.

It is noteworthy that the blue dye which was completely eliminated by75% persulfate/25% carbonate alone, was a copper-based dye. Thus, eventhough copper was not added, the in situ copper provided by the dyeplayed an important role in the decolorization process. The copper/AscOHenhanced persulfate/carbonate was effective toward a wider range of dyesthan persulfate/carbonate alone.

Example 6 Experimental Decolorization Formulations III

This example illustrated the decolorization efficacy of a 75%persulfate/25% carbonate/copper/saccharide formulation using cis-hydroxysaccharides including D-sorbitol, L-sorbose, D-ribose, D-mannitol,D-glucose, and D-galactose.

The standard rollermill and repulping procedures were used. Arose-colored tissue paper containing wet strength resin was treated atan application rate of 5% owf with a formulation containing 97.99% ofBT-100, 2.00% saccharide, and 0.01% iron sulfate. The results areillustrated in Table 6 below.

                  TABLE 6                                                         ______________________________________                                        Experimental Decolorization Formulations III                                  Evaluation of Saccharide Decolorization Activators                                                        (+ / -) (+ / -)                                   Treatment.sup.1                                                                        Brightness                                                                             Lightness Red/Green                                                                             Yellow/Blue                               ______________________________________                                        Control A.sup.2                                                                        43.48    73.10     16.9    1.5                                       Control B.sup.3                                                                        53.24    79.44     11.3    2.6                                       D-sorbitol                                                                             60.28    83.72     5.1     3.6                                       L-sorbose                                                                              52.27    78.31     13.5    1.8                                       D-ribose 50.45    77.16     14.7    1.7                                       D-mannitol                                                                             53.60    80.44     8.9     4.3                                       D-glucose                                                                              50.75    77.98     12.7    2.8                                       D-galactose                                                                            51.07    77.73     13.2    1.9                                       ______________________________________                                         .sup.1 Each saccharide formulation contained 97.99% of (BT100), 2.00%         saccharide and 0.01% FeSO.sub.4.                                              .sup.2 No formulation used. Repulped with caustic addition to pH 10.          .sup.3 Repulped with 75% persulfate/25% carbonate alone. There was no         saccharide or metal addition.                                            

Table 6 illustrates that persulfate/carbonate alone effectively improvedISO brightness (53.24 vs 43.48) and lightness (79.44 vs 73.10) comparedto pH 10 treatment. The paper was also less red, but yellownessincreased slightly. Improvements in each category were afforded bysupplemental treatments with D-sorbitol/Cu and D-mannitol/Cu. For each acombination of high brightness and lightness as well as low red/greenand yellow/blue values were noted. The reduction in red value of thisrose-colored paper was readily apparent. D-sorbitol provided the bestreduction (5.1) with D-mannitol being next best (8.9).

Example 7 Repulping of Rose-Colored Paper

Example 7 illustrates the repulping of a rose-colored, wet strengthpaper and compares the effectiveness of sodium persulfate and acarbonate with (treatment B) and without (treatment A) copper.

The rollermill and repulping procedures described above were employed,and the results described in Table 7. The first tap water of the daycontaining 1 ppm Cu was used where the water source "tap" is indicatedin Table 7. The deionized water contained no copper. As Table 7illustrates, copper enhances the repulping efficacy of alkaline sodiumpersulfate. This is evidenced by the approximately 40% reduction inrepulp time afforded by 1 ppm copper.

Comparing Deionized and Tap Water

                  TABLE 7                                                         ______________________________________                                        Repulping of Rose-Colored Paper                                                                           Time to Achieve                                                                         Copper                                  Treatment                                                                            Furnish (%)                                                                             Water Source                                                                             Stage 6 (min)                                                                           (ppm)                                   ______________________________________                                        A      5         Deionized  35        0                                       A      5         Tap        20        1                                       B      5         Deionized  25        0                                       B      5         Tap        15        1                                       ______________________________________                                         A = 75% sodium persulfate/25% calcium carbonate (BT100)                       B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                             

Example 8 Effect of Copper Content of Dye on Decolorizing Efficacy I

Example 8 illustrates the decolorization of a wet strength tissue paper,which was dyed blue with a copper containing dye. The rollermill andrepulping procedures described above were employed, and the resultsdescribed in Table 8. A 15 minute repulping time was employed.

                  TABLE 8                                                         ______________________________________                                        Decolorizing Efficacy                                                         Blue Facial Tissue                                                                            ISO             (+ / -)                                                                              (+ / -)                                Treatment                                                                             Furnish Brightness                                                                             Lightness                                                                            Red/Green                                                                            Yellow/Blue                            ______________________________________                                        Blue Facial                                                                           0       72.59    83.27  -7.2   -8.4                                   A       5%      79.86    90.73  -1.3   -1.0                                   B       5%      83.68    94.02  -0.6     1.8                                  C       5%      86.51    95.20  -0.7     1.5                                  ______________________________________                                         A = 75% sodium persulfate/25% sodium carbonate                                B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                                  C = Oxone ® peroxygen; Oxone, a trademark of DuPont Inc. for              2 KHSO.sub.5.K.sub.2 SO.sub.4.KHSO.sub.4, which has the active ingredient     potassium caroate, a peroxymonosulfate.                                  

As illustrated in Table 8, each of the three formulations tested workedwell in decolorizing this copper containing dye. In each case theyellow/blue value was less than 3 indicating that the residual dye wasnot visible to the eye.

Example 9 Effect of Copper Content of Dye on Decolorizing Efficacy II

Example 9 illustrates the decolorization of wet strength paper coloredwith a copper containing green dye. The rollermill and repulpingprocedures described above were employed, and the results described inTable 9. A 15 minute repulping time was employed.

                  TABLE 9                                                         ______________________________________                                        Decolorizing Efficacy                                                         Green Toilet Tissue                                                                           ISO             (+ / -)                                                                              (+ / -)                                Treatment                                                                             Furnish Brightness                                                                             Lightness                                                                            Red/Green                                                                            Yellow/Blue                            ______________________________________                                        Green Tissue                                                                          0       63.61    86.71  -17.4  5.0                                    A       5%      85.13    95.29  -1.8   2.9                                    B       5%      85.86    95.83  -1.2   3.4                                    C       5%      83.92    95.05    1.1  3.2                                    ______________________________________                                         A = 75% sodium persulfate/25% sodium carbonate                                B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                                  C = Oxone ® peroxygen                                                

The data provided in Tables 8 and 9 illustrates that the addition ofcopper ion effectively enhances the decolorization performance ofpersulfates.

Example 10 Effect of Copper Content of Dye on Decolorizing Efficacy III

Example 10 illustrates the decolorization of a rose-colored, wetstrength paper, which did not employ a copper containing dye. Therollermill and repulping procedures described above were employed, andthe results described in Table 10. A 15 minute repulping time wasemployed.

                  TABLE 10                                                        ______________________________________                                        Decolorizing Efficacy                                                         Rose Toilet Tissue                                                                            ISO             (+ / -)                                                                              (+ / -)                                Treatment                                                                             Furnish Brightness                                                                             Lightness                                                                            Red/Green                                                                            Yellow/Blue                            ______________________________________                                        Rose Tissue                                                                           0       61.43    82.13  22.8   -0.5                                   A       5%      74.08    92.06  4.1    6.2                                    B       5%      83.53    94.87  1.6    3.3                                    C       5%      83.57    94.67  1.8    2.2                                    ______________________________________                                         A = 75% sodium persulfate/25% sodium carbonate                                B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                             

In Table 10 enhanced decolorization for a mixture of persulfate and basein the presence of copper is illustrated.

Example 11 Effect of Copper Content of Dye on Decolorizing Efficacy IV

Example 11 illustrates the decolorization of a yellow colored, wetstrength tissue paper, which did not employ a copper containing dye. Therollermill and repulping procedures described above were employed, andthe results described in Table 11. A 15 minute repulping time wasemployed.

                  TABLE 11                                                        ______________________________________                                        Decolorizing Efficacy                                                         Yellow Toilet Tissue                                                                          ISO             (+ / -)                                                                              (+ / -)                                Treatment                                                                             Furnish Brightness                                                                             Lightness                                                                            Red/Green                                                                            Yellow/Blue                            ______________________________________                                        Yellow  0       56.44    95.38  -2.6   26.4                                   Tissue                                                                        A       5%      73.84    95.55  -0.9   11.5                                   B       5%      85.23    96.15  -0.2   4.1                                    C       5%      85.68    96.31  0      4.2                                    ______________________________________                                         A = 75% sodium persulfate/25% sodium carbonate                                B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                                  C = Oxone                                                                

Table 11 illustrates that copper was required for effectivedecolorization of the yellow dye used in this example.

Example 12 Effect of pH on Decolorizing Efficacy

Example 12 illustrates the decolorization of a rose-colored, wetstrength paper, which did not employ a copper containing dye. Therollermill and repulping/decolorizing procedures described above wereemployed, and the results described in Table 12. A 15 minutedecolorizing time was employed. The initial pH was recorded when thetreatment "Control" or "B" was added to the system.

                  TABLE 12                                                        ______________________________________                                        Decolorizing Efficacy                                                         Rose Paper                                                                    Treat-                                                                              OWF           ISO           (+ / -)                                                                              (+ / -)                              ment  (%)    pH.sub.i                                                                             Brightness                                                                           Lightness                                                                            Red/Green                                                                            Yellow/Blue                          ______________________________________                                        Control                                                                             0      10.0   43.48  73.10  16.9   1.5                                  B     5      2.1*   61.16  85.63  5.2    6.8                                  B     5      4.0*   58.60  85.12  5.7    7.3                                  B     5      7.1*   65.99  88.06  3.2    5.8                                  B     5      8.3    60.17  83.74  5.0    3.8                                  B     5      10.5.sup.+                                                                           57.68  81.86  10.1   2.6                                  ______________________________________                                         B = 75% sodium persulfate/24.5% sesquicarbonate/0.50% copper sulfate          pentahydrate                                                                  *pH adjusted with sulfuric acid, H.sub.2 SO.sub.4                             .sup.+ pH adjusted with sodium hydroxide, NaOH                           

Table 12 illustrates the effectiveness of persulfate and copper as adecolorizer over a wide pH range, extending from about 2 to about 10.5,with the best decolorizing occurring within the range of about 2 toabout 9.5.

Example 13 Effect of pH on Repulping Efficacy

Example 13 illustrates the repulping of a rose-colored, wet strengthpaper, which did not employ a copper containing dye. The rollermill andrepulping procedures described above were employed, and the resultsdescribed in Table 13.

                  TABLE 13                                                        ______________________________________                                        Repulping Efficacy                                                            Rose Paper                                                                               OWF                  Time to achieve                               Treatment  (%)    pH.sub.i pHf  Stage 6 (min)                                 ______________________________________                                        B          5      2.1*     2.2  35                                            B          5      4.0*     2.6  30                                            B          5      7.1*     3.7  20                                            B          5      8.3      6.4  15                                            B          5      10.5.sup.+                                                                             8.3  15                                            ______________________________________                                         B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                                  *pH adjusted with sulfuric acid, H.sub.2 SO.sub.4                             .sup.+ pH adjusted with sodium hydroxide, NaOH                           

Table 13 illustrates the effectiveness of persulfate and copper salt inrepulping within a pH range of from 2.1 to 10.5. Repulping efficacy wasgood over the entire pH range tested; yet, it improved further as the pHincreased from slightly acidic (>4) to basic. This study indicates thatat a pHi >7 efficacy is further improved, and that greatest repulpingefficacy occurs at a pHi >8.

Example 14 Effect of Temperature on Decolorizing Efficacy

Example 14 illustrates the decolorization of a rose-colored, wetstrength paper, which did not employ a copper containing dye. Therollermill and repulping/decolorizing procedures described above wereemployed, and the results described in Table 14. A 15 minute repulpingtime was employed, and decolorization occurred at the indicatedtemperature.

                  TABLE 14                                                        ______________________________________                                        Decolorizing Efficacy                                                         Rose Paper                                                                    Treat-                                                                              OWF    Temp   ISO           (+ / -)                                                                              (+ / -)                              ment  (%)    C.     Brightness                                                                           Lightness                                                                            Red/Green                                                                            Yellow/Blue                          ______________________________________                                        Control                                                                             0      70     43.48  73.10  16.9   1.5                                  A     5      40     39.64  71.41  21.6   3.8                                  B     5      40     40.86  72.35  17.8   4.0                                  A     5      50     41.42  72.62  20.8   3.8                                  B     5      50     45.92  76.55  12.1   5.5                                  A     5      70     51.52  79.36  10.6   4.2                                  B     5      70     60.17  83.74  5.0    3.8                                  ______________________________________                                         A = 75% sodium persulfate/25% sodium carbonate                                B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                             

Table 14 illustrates that decolorization begins to occur at about 50° C.or higher when a dyed paper was treated with sodium persulfate andcopper sulfate. Without copper salt decolorization began to occur at 70°C., but not at a satisfactory level.

Example 15 Effect of Temperature on Repulping Efficacy

Example 15 illustrates the repulping of a rose-colored, wet strengthpaper, which did not employ a copper containing dye. The rollermill andrepulping/decolorizing procedures described above were employed, and theresults described in Table 15. Repulping occurred at the indicatedtemperature.

                  TABLE 15                                                        ______________________________________                                        Repulping Efficacy                                                            Rose Paper                                                                             OWF             Temperature                                                                            Time to achieve                             Treatment                                                                              (%)     pH.sub.i                                                                              (C.)     Stage 6 (min)                               ______________________________________                                        A        5       8.6     40       60                                          B        5       8.5     40       50                                          A        5       8.9     50       60                                          B        5       8.0     50       30                                          A        5       8.4     70       20                                          B        5       8.3     70       15                                          ______________________________________                                         A = 75% sodium persulfate/25% sodium carbonate                                B = 75% sodium persulfate/24.5% sodium sesquicarbonate/0.5% copper sulfat     pentahydrate                                                             

Table 15 illustrates that repulping occurred at 40° C. with repulpingefficacy improving as the temperature increased. Also, the presence ofcopper improved the repulping efficacy over what was attainable byrepulping without copper.

Example 16 Effect of Alkalinity Source on Decolorizing Efficacy

Example 16 illustrates the decolorization of a rose-colored, wetstrength paper napkin, which did not employ a copper containing dye. Therollermill and repulping/decolorizing procedures described above wereemployed, and the results described in Table 16. A 15 minute repulpingtime was employed, and decolorization occurred under the pH conditionsindicated.

                  TABLE 16                                                        ______________________________________                                        Decolorizing Efficacy                                                         Rose Paper                                                                    Treat-                                                                              Furnish        ISO    Light-                                                                              (+ / -)                                                                              (+ / -)                              ment  (%)     pH.sub.i                                                                             Brightness                                                                           ness  Red/Green                                                                            Yellow/Blue                          ______________________________________                                        Control                                                                             0       10.0   43.48  73.10 16.9   1.5                                  SP/Cu/                                                                              5       9.0*   65.60  88.05 3.3    6.1                                  NaOH                                                                          SP/Cu/                                                                              5       7.6.sup.+                                                                            55.04  84.21 4.5    9.5                                  Na.sub.2 SO.sub.4                                                             ______________________________________                                         Control = caustic solution without persulfate or copper                       SP = Sodium persulfate, Cu = copper sulfate pentahydrate                      *= NaOH added as alkali and to increase pH.                                   .sup.+ = Na.sub.2 SO.sub.4 added as alkali and to increase pH.           

Table 16 illustrates the efficacy of sodium persulfate with copper ionfor reducing color using sodium hydroxide or sodium sulfate as the pHadjuster. Using sodium hydroxide as the base, there was a reduction ofthe red color to an acceptable value of 3.3. Similarly, using sodiumsulfate as the base there was a marked reduction in the red value to4.5; it is expected that the red value would decrease further with asmall increase in processing time. The increase in yellow value may havebeen imparted by the high concentration of sulfate used when Na₂ SO₄ wasused to adjust the pH. Generally, it is believed that with sufficientcontact time, the yellow values will decrease further. In someinstances, however, it may be more expedient or necessary to select adifferent pH adjuster or to use less of a particular pH adjuster thatmay be causing a color problem in conjunction with more of another pHadjuster.

Example 17 Effect of Alkalinity Source on Repulping Efficacy

Example 17 illustrates the repulping of a rose-colored, wet strengthpaper, which did not employ a copper containing dye. The rollermill andrepulping/decolorizing procedures described above were employed, and theresults described in Table 17. A 15 minute repulping time was employed,and repulping occurred under the pH conditions indicated.

                  TABLE 17                                                        ______________________________________                                        Repulping Efficacy                                                            Rose Paper                                                                              Furnish                 Time to achieve                             Treatment (%)       pH.sub.i                                                                              pH.sub.f                                                                            Stage 6 (min)                               ______________________________________                                        B         5         8.3     6.4   15                                          75% SP/   5         9.0*    3.71  25                                          0.5% Cu/                                                                      24.5% NaOH                                                                    75% SP/   5         7.6.sup.+                                                                             4.52  25                                          0.5% Cu/                                                                      24.5% Na.sub.2 SO.sub.4                                                       ______________________________________                                         B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                                  SP = Sodium persulfate, Cu = copper sulfate pentahydrate                      *= NaOH added as alkali and to increase pH.                                   .sup.+ = Na.sub.2 SO.sub.4 added as alkali and to increase pH.                pH.sub.i = initial pH                                                         pH.sub.f = final pH                                                      

Table 17 illustrates that the sesquicarbonate which produces an initialpH of 8.3 is the best alkalinity source for minimizing repulping time;however, each of the treatments tested at each pH employed produced goodresults.

Example 18 Repulping Toweling Grades with Copper Activated Persulfate

Example 18 illustrates the repulping of a variety of grades of toweling,using sodium persulfate with copper and a base such as sodium carbonateor sodium sesquicarbonate. The rollermill and repulping/decolorizingprocedure described above were employed, and the results are presentedin Table 18.

                  TABLE 18                                                        ______________________________________                                        Repulping Toweling Grades with Copper Activated Persulfate                                                Time to Achieve                                   Treatment                                                                            Furnish (%)                                                                             Broke Type Stage 6 (min)                                                                            Copper                                 ______________________________________                                        A      5         Plain Towel                                                                              40         No                                     B      5         Plain Towel                                                                              20         Yes                                    A      5         Printed Towel                                                                            50         No                                     B      5         Printed Towel                                                                            20         Yes                                    A      5         Yellow Towel                                                                             30         No                                     B      5         Yellow Towel                                                                             20         Yes                                    ______________________________________                                         A = 75% sodium persulfate/25% sodium carbonate                                B = 75% sodium persulfate/24.5% sesquicarbonate/0.5% copper sulfate           pentahydrate                                                             

Tables 7 and 18 above illustrate the enhanced repulping effect providedby copper in the repulping formulation, with the time for repulpingbeing reduced on the average by about 50% as evidenced by the reportedtimes for achieving stage 6.

Example 19 Repulping Comparison: Persulfate/Copper and Peroxymonosulfate

Example 19 illustrates the repulping of various, wet strength papers,and compares the efficacy of a caroate containing formulation to anembodiment of this invention. The rollermill and repulping proceduresdescribed above were employed, and the results described in Table 19.

                  TABLE 19                                                        ______________________________________                                        Repulping Comparison: Persulfate/Copper and                                   Peroxymonosulfate                                                                                         Time to Achieve                                   Treatment                                                                            OWF (%)  Broke Type  Stage 6 (min)                                                                           Copper                                  ______________________________________                                        B      5        Plain Towel 20        Yes                                     C      5        Plain Towel 20        No                                      B      5        Printed Towel                                                                             20        Yes                                     C      5        Printed Towel                                                                             30        No                                      B      5        Yellow Towel                                                                              20        Yes                                     C      5        Yellow Towel                                                                              30        No                                      ______________________________________                                         B = 75% sodium persulfate/24.5% sodium sesquicarbonate/0.5% copper sulfat     pentahydrate                                                                  C = Oxone ® peroxygen                                                

As illustrated in Table 19, copper when used with sodium persulfate andsodium sesquicarbonate provides an enhanced repulping time relative to acaroate-based peroxygen.

Example 20 Decolorization with Sorbitol/Cu and Ascorbic Acid/Cu

This example illustrates the decolorization efficacy of variousformulations on a rose-colored paper. Hypochlorite was used as astandard, as it has been, and is, the industry standard. Oxone was usedbecause it has been commercially used for both decolorization andrepulping. The rollermill and repulping procedures described above wereused. Formulations were applied at 5% owf. Ascorbic acid, likeD-sorbitol has a cis-hydroxyl group.

The results of this study are provided in Table 20 below.

                  TABLE 20                                                        ______________________________________                                        Decolorization with                                                           Sorbitol/Cu and Ascorbic Acid/Cu                                                                          (+ / -) (+ / -)                                   Treatment                                                                              Brightness                                                                             Lightness Red/Green                                                                             Yellow/Blue                               ______________________________________                                        *Control 43.48    73.10     16.9    1.5                                       2% BT-100                                                                              48.84    76.49     14.5    2.4                                       4% BT-100                                                                              52.06    79.42     10.7    4.0                                       6% BT-100                                                                              53.21    80.53     10.4    4.7                                       5% BT-100                                                                     + Cu.sup.1 /Asc.sup.2                                                                  60.26    84.90     3.5     5.2                                       5% BT-100                                                                     + Cu.sup.1 /Sor.sup.3                                                                  69.76    88.52     2.8     3.4                                       Oxone 5% 67.20    84.13     9.7     -2.6                                      OCI.sup.- 2%                                                                           79.87    93.55     1.7     3.7                                       ______________________________________                                         *The Control is caustic solution pH.sub.i 10 only.                            .sup.1 Cu added at 1 ppm from CuSO.sub.4.5H.sub.2 O                           .sup.2 Asc = ascorbic acid.                                                   .sup.3 Sor = Dsorbitol.                                                  

A mixture of 75% sodium persulfate and 25% sodium carbonate at 6% OWFeffectively improved ISO brightness (53.21 vs 43.48) and lightness(80:53 vs 73,10) compared to the pH 10 treatment. The paper was alsoless red, but yellowness increased slightly.

The persulfate/carbonate formulation was somewhat effective atincreasing levels. A significant improvement in decolorization wasachieved when either ascorbic acid/copper or D-sorbitol/copper was addedwith persulfate and carbonate. Either treatment yielded a pulp that wasbetter than the Oxone treatment for reducing the red value associatedwith rose-colored paper napkin. However, hypochlorite (OCI⁻) wasslightly better than any of the non-chlorine treatments for red colorreduction.

In this study, enhanced persulfate systems were more effective thanperoxymonosulfate, but not as effective as the hypochlorite.

Example 21 Decolorization with Saccharide/Copper Mixtures

Example 21 illustrates the decolorization efficacy of three enhancedpersulfate/carbonate uses with D-sorbitol/Cu, D-mannitol/Cu, or copper.A broke derived from a wet strength resin containing rose-colored paperwas used as the paper sample. The repulping and rollermill proceduresdescribed herein were used. The results are illustrated in Table 21 andthe formulations are presented in Table 21A.

                  TABLE 21                                                        ______________________________________                                        Decolorization with Saccharide/Copper Mixtures                                                            (+ / -) (+ / -)                                   Treatment                                                                             Brightness                                                                              Lightness Red/Green                                                                             Yellow/Blue                               ______________________________________                                        Form. 1 52.87     78.75     11.3    2.2                                       Form. 2 60.17     83.74     5.0     3.8                                       Form. 3 58.82     83.37     5.4     4.5                                       Form. 4 64.12     85.08     4.7     2.6                                       ______________________________________                                    

                  TABLE 21A                                                       ______________________________________                                        Formulations                                                                                 Chemical                                                       Formulation    Composition                                                                              % w/w                                               ______________________________________                                        1              BT-100     100                                                 2              BT-100     99.50                                                              CuSO.sub.4.5H.sub.2 O                                                                    0.50                                                3              BT-100     97.50                                                              D-sorbitol 2.00                                                               CuSO.sub.4.5H.sub.2 O                                                                    0.50                                                4              BT-100     47.50                                                              D-mannitol 2.00                                                               CuSO.sub.4.5H.sub.2 O                                                                    0.50                                                ______________________________________                                    

In Table 21, the two copper enhanced formulations were essentially equalin reducing the red value associated with the rose-colored paper napkin.All other values (brightness, lightness, red/green, and yellow/blue)were also essentially equal. Both were markedly superior to formulation1, which did not contain copper.

We claim as follows:
 1. A dry formulation for repulping and/ordecolorizing a wet strength broke, comprising a mixture of:51 to 94weight % persulfate; 4 to 43 weight % pH adjuster; 0.05 to 6 weight %soluble catalyst, said catalyst selected from the group consisting ofsoluble salts of copper, soluble salts of iron, soluble salts of silver,soluble salts of nickel, and mixtures of said salts; and 0-10 weight %of a saccharide which has no greater ability to reduce the catalyst thanD-mannitol.
 2. The formulation of claim 1, wherein the pH adjuster is abase selected from the group consisting of alkali metal or alkalineearth metal salt of carbonates bicarbonate or sesquicarbonate;thecatalyst is a copper salt; the saccharide is a cis-alpha-hydroxysaccharide; and the formulation contains 61-85 weight % persulfate, 14to 39 weight % base, 1 to 6% cis-alpha-hydroxy-saccharide and 0.05 to 3weight % copper salt.
 3. The formulation of claim 1 in which the pHadjuster is selected from the group consisting of sodium carbonate,sodium bicarbonate, potassium carbonate, potassium bicarbonate, calciumcarbonate, sodium sesquicarbonate, and potassium sesquicarbonate.
 4. Theformulation of claim 1, wherein;the pH adjuster is a base selected fromthe group consisting of alkali metal, alkaline earth metal, or ammoniumsalt of carbonate, bicarbonate or sesquicarbonate; the catalyst is acopper salt; the saccharide is selected from the group consisting of oneor more of ascorbic acid, D-sorbitol, and D-mannitol; and theformulation contains 61 to 85 weight % persulfate, 14 to 39 weight %base, 0-4 weight % saccharide and 0.05 to 3.0 weight % copper salt. 5.The formulation of claim 4, wherein the mixture contains 70 to 80 weight% persulfate, 20 to 29 weight percent sesquicarbonate, and 0.1 to 2weight % copper salt.
 6. The formulation of claim 4, wherein the mixturecontains 70 to 80 weight % persulfate 20 to 29 weight % sesquicarbonate,0.1 to 2 weight % copper salt, and 1 to 3 weight % cis-alphahydroxysaccharide.
 7. The formulation of claim 4 in which the pH adjuster isselected from the group consisting of sodium carbonate, sodiumbicarbonate, potassium carbonate, potassium bicarbonate, calciumcarbonate, sodium sesquicarbonate, and potassium sesquicarbonate.